In any transportation industry, reliable communications systems are mandatory for avoiding serious, if not catastrophic, accidents. In the particular case of the railroads, reliable and secure communications must be maintained between railroad central offices, railroad locomotives, service vehicles operating on railway tracks, and wayside systems, among other things.
Railroad central offices normally communicate with a network of wireless base stations through wired telecommunications links. These base stations then support wireless communications with locomotives, service vehicles, and wayside systems. Electronic train management systems (ETMS) allow locomotives to communicate directly (peer-to-peer) with the wayside systems and base stations using on-board radios. The locomotives are therefore able to receive, for example, up-to-date wayside aspect information, track database updates, and track authorizations, well before the wayside systems (e.g. signals) are within sight.
Remote wayside interface systems monitor a corresponding set of wayside systems such as signals, switches, and track circuits and directly provide the locomotives with real-time critical aspect and status information. In addition to directly communicating with the locomotives, the wayside interface systems also provide this wayside status and aspect information to the central office via the network of base stations.
Given the criticality of the information being gathered and transmitted, reliability and security are key features in wayside interface system design and construction. Among other things, these systems must accurately ascertain the current state of the monitored signals, switches, and/or track circuits and then transmit that information to oncoming locomotives with minimal error. Furthermore, wayside interface systems must be substantially robust to withstand potentially severe field conditions, as well as be resistant to tampering and similar intentional human interference.